rpl.rpl_flushlog_loop failed in buildbot with non-specific server crash

rpl.rpl_flushlog_loop 'mix'              w3 [ fail ]  Found warnings/errors in server log file!

        Test ended at 2020-01-17 18:34:04

line

Attempting backtrace. You can use the following information to find out

^ Found warnings in /dev/shm/var/3/log/mysqld.1.err

ok

2020-01-17 18:34:03 281472951287968 [Note] Slave SQL thread exiting, replication stopped in log 'slave-bin.000001' at position 1049

2020-01-17 18:34:03 281472951681184 [Note] Slave I/O thread exiting, read up to log 'slave-bin.000001', position 1049

200117 18:34:03 [ERROR] mysqld got signal 6 ;

This could be because you hit a bug. It is also possible that this binary

or one of the libraries it was linked against is corrupt, improperly built,

or misconfigured. This error can also be caused by malfunctioning hardware.

To report this bug, see https://mariadb.com/kb/en/reporting-bugs

We will try our best to scrape up some info that will hopefully help

diagnose the problem, but since we have already crashed, 

something is definitely wrong and this may fail.

Server version: 10.2.31-MariaDB-log

key_buffer_size=1048576

read_buffer_size=131072

max_used_connections=4

max_threads=153

thread_count=6

It is possible that mysqld could use up to 

key_buffer_size + (read_buffer_size + sort_buffer_size)*max_threads = 63023 K  bytes of memory

Hope that's ok; if not, decrease some variables in the equation.

Thread pointer: 0x0

Attempting backtrace. You can use the following information to find out

where mysqld died. If you see no messages after this, something went

terribly wrong...

stack_bottom = 0x0 thread_stack 0x49000

2020-01-17 18:34:03 281472952860832 [Note] Master connection name: ''  Master_info_file: 'master.info'  Relay_info_file: 'relay-log.info'

2020-01-17 18:34:03 281472952860832 [Note] 'CHANGE MASTER TO executed'. Previous state master_host='127.0.0.1', master_port='16061', master_log_file='slave-bin.000001', master_log_pos='1049'. New state master_host='127.0.0.1', master_port='16061', master_log_file='', master_log_pos='1049'.

/usr/sbin/mysqld(my_print_stacktrace+0x3c)[0xaaaab5d1db0c]

/usr/sbin/mysqld(handle_fatal_signal+0x48c)[0xaaaab580572c]